This invention relates to lubricant greases and to a method for preparing the same. More particularly, this invention concerns itself with lubricating greases composed of perfluoropolyether fluids thickened with a thickening material composed of a mixture of a silicone fluid and a substituted polyphenylene.
The present utilization of machinery and equipment within high temperature and high stress environments has created a need for lubricating compositions that demonstrate a high degree of stability within such an environment. For example, loaded ball bearings are often required to perform in intermittent operations at high speed, high temperature and high pressure, and it has become increasingly difficult to formulate lubricants which fulfill the need for thermally stable greases.
The use of a perfluoropolyether fluid thickened to a grease consistency has been suggested as a material suitable for use in lubricating loaded bal bearings. It is also known that polyphenylene compounds are effective thickeners for perfluoropolyether. However, the resultant lubricant does not possess sufficient stability against the effects of thermal degradation to warrant its use at greatly increased temperatures.
With the present invention, however, it has been discovered that the addition of a silicone fluid improves the thickening efficiency of substituted polyphenylenes when the polyphenylenes are used to convert perfluoropolyether fluids to a grease consistency.